The use of thin aerogel sheets to suppress the thermal runaway propagation of high energy density cells (LiNi_0.8Co_0.1Mn_0.1O₂/Si-C) based module

Safety issue is the main concern for current lithium-ion batteries (LIBs), especially for the high energy density cells based on nickel-rich oxide/Si-C chemistries, which could experience violent explosion and intense burning with the temperature exceeding 1000 °C during thermal runaway (TR). And moreover, within a module/system, the TR of a single cell might trigger the TR of neighboring cells, usually called TR propagation, leading to a fire accident or even a server disaster. The objective of this work is to introduce an aerogel sheet with extremely low thermal conductivity and high thermal stability to block the TR propagation. The silica aerogel sheet (SAS) is synthesized via a sol-gel process followed by supercritical fluid drying. The thermal conductivities of the obtained SAS are 0.018, 0.029, 0.043 and 0.074 W (m·K) ⁻¹ at 20 °C, 300 °C, 500 °C and 800 °C, respectively. A simple module is constructed with two LIBs (NCM811/Si-C, 320 Wh/kg) sandwiched with a piece of SAS with various thicknesses (1.2–2.8 mm). The results show that the SAS of 1.2 mm or 1.8 mm thickness cannot stop the TR propagation. The propagation times to next cell are 50 (1.2 mm) and 106 s (1.8 mm), respectively. While the SAS of 2.3 mm or thicker can suppress the TR propagation successfully, and moreover, protect the neighboring cell from any voltage drop/collapse. The microstructure and thermal conductivity of the SAS after TR experiments do not show evident change, revealing that the as-prepared SAS is thermally stable during the violent TR process. This work provides new insights for battery thermal management system (BTMS).